Conventionally, in order to enhance moist rich sensations, smooth spreadability, and emollient sensations, skin cosmetics have been prepared by blending in polyhydric alcohols such as glycerin, 1,3-butylene glycol, and dipropylene glycol as water-based ingredients, and then solid oils including higher fatty acids such as stearic acid, palmitic acid, myristic acid, and behenic acid, waxes such as petrolatum, carnauba wax, candelilla wax, ceresin, and microcrystalline wax, and higher alcohols such as lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, and behenyl alcohol are blended in, followed by emulsification using an emulsifying agent, to obtain an oil-in-water emulsified cosmetic.
In order to suppress crystal precipitation of these solid oils over time, attempts have been made to avoid crystal precipitation of the solid oils by adding hydrocarbon oils that are compatible with said solid oils and are liquid at ordinary temperatures such as liquid paraffin and squalane, and ester oils having relatively long carbon chains, equivalent in length to the carbon chains of the solid oils, such as cetyl palmitate, isopropyl isostearate, isodecyl pivalate, and oleyl oleate (for example, refer to Non-Patent Document 1).
However, oil-in-water emulsified skin cosmetics prepared with the method as described above, when applied on the skin, manifest emollient sensations and taut sensations but spreadability and absorption into the skin are not good, and they are sticky, resulting in an unsatisfactory usability.
On the other hand, when solid oils are not added, the products are superior in that spreadability and absorption into the skin are good and there is no stickiness, but an absence of the emollient sensation and taut sensation becomes problematic.
In recent years, skin cosmetics using homopolymers or copolymers having acrylic acid and/or acrylamide skeletons and pentaerythritol ester or dipentaerythritol ester and/or tripentaerythritol have been proposed.
However, for these skin cosmetics, even though they could give a good emollient sensation to the skin, the stickiness after the application was not sufficiently reduced (for example, see Patent Document 1).
In the field of skin cosmetics, for the purpose of improving the smoothness at the time of the application and reducing the stickiness after application, it has been known to use paste-like silicon elastomers prepared by using various liquid oil agents such as dimethicone and trioctanoin as the solvent for the following: silicone oils such as decamethylcyclopentasiloxane, dimethylpolysiloxane, methylphenylpolysiloxane, methylphenylpolysiloxane, caprylyl methicone, and methylhydrogenpolysiloxane; silicone rubbers such as high polymer dimethylpolysiloxane and amino-modified high polymer dimethylpolysiloxane; three-dimensional silicone cross-linked compounds such as (dimethicone/vinyl dimethicone) crosspolymers, (dimethicone/phenyl dimethicone) crosspolymers, (vinyl dimethicone/lauryl dimethicone) crosspolymers, (lauryl dimethicone/polyglycerin-3) crosspolymers, (lauryl polydimethylsiloxyethyl dimethicone/bis vinyl dimethicone) crosspolymers, and dimethicone crosspolymers.
However, when they were blended into oil-in-water emulsified skin cosmetics, compatibility with other oil components, such as hydrocarbon oils, ester oils, waxes, etc., in the oil phase had to be taken into account, which put constraints on formulation configurations (for example, see Patent Document 2 and Patent Document 3).
Furthermore, when oil-based ingredients such as silicones, esters, and hydrocarbons were to be blended into a water-based base agent, they needed to be emulsified, and hence an emulsifying agent was needed; this oftentimes caused an additional problem of stickiness due to the emulsifying agent.